System philosophy
HARDWARE REFERENCE MANUAL
50
Revi
si
on 3.0
2.9
Mechanical system
2.9.1
Inertia ratio
The inertia ratio is a stability criterion. The higher the intertia of the
load in relation to the intertia of the motor, the lower the gains you
can set in your system before you reach oscillation, and the lower
the performance you can reach.
With a ratio of 1:30 for small Servo Drivers and a ratio of 1:5 for big
Servo Drivers you can reach the maximum dynamic of the motor-
driver combination.
2.9.2
Rigidity
If a machine is more rigid and less elastic, you can set higher gains
without vibration, and you can reach higher dynamic and lower
Following Error.
2.9.3
Resonant frequency
A mechanical system has at least one resonant frequency. If you
excite your mechanical system to the resonant frequency, it starts
oscillating. For motion systems, it is best to have mechanical
systems with a very high resonant frequency, that is, with low
inertia and high rigidity.
The resonant frequency of the mechanical system is the limit for
the gain settings.
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